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1/* nicstar.c v0.22 Jawaid Bazyar (bazyar@hypermall.com)2 * nicstar.c, M. Welsh (matt.welsh@cl.cam.ac.uk)3 *4 * Hacked October, 1997 by Jawaid Bazyar, Interlink Advertising Services Inc.5 * http://www.hypermall.com/6 * 10/1/97 - commented out CFG_PHYIE bit - we don't care when the PHY7 * interrupts us (except possibly for removal/insertion of the cable?)8 * 10/4/97 - began heavy inline documentation of the code. Corrected typos9 * and spelling mistakes.10 * 10/5/97 - added code to handle PHY interrupts, disable PHY on11 * loss of link, and correctly re-enable PHY when link is12 * re-established. (put back CFG_PHYIE)13 *14 * Modified to work with the IDT7721 nicstar -- AAL5 (tested) only.15 *16 * R. D. Rechenmacher <ron@fnal.gov>, Aug. 6, 199717 *18 * Linux driver for the IDT77201 NICStAR PCI ATM controller.19 * PHY component is expected to be 155 Mbps S/UNI-Lite or IDT 77155;20 * see init_nicstar() for PHY initialization to change this. This driver21 * expects the Linux ATM stack to support scatter-gather lists 22 * (skb->atm.iovcnt != 0) for Rx skb's passed to vcc->push.23 *24 * Implementing minimal-copy of received data:25 * IDT always receives data into a small buffer, then large buffers26 * as needed. This means that data must always be copied to create27 * the linear buffer needed by most non-ATM protocol stacks (e.g. IP)28 * Fix is simple: make large buffers large enough to hold entire29 * SDU, and leave <small_buffer_data> bytes empty at the start. Then30 * copy small buffer contents to head of large buffer.31 * Trick is to avoid fragmenting Linux, due to need for a lot of large32 * buffers. This is done by 2 things:33 * 1) skb->destructor / skb->atm.recycle_buffer34 * combined, allow nicstar_free_rx_skb to be called to35 * recycle large data buffers36 * 2) skb_clone of received buffers37 * See nicstar_free_rx_skb and linearize_buffer for implementation38 * details.39 *40 *41 *42 * Copyright (c) 1996 University of Cambridge Computer Laboratory43 *44 * This program is free software; you can redistribute it and/or modify45 * it under the terms of the GNU General Public License as published by46 * the Free Software Foundation; either version 2 of the License, or47 * (at your option) any later version.48 * 49 * This program is distributed in the hope that it will be useful,50 * but WITHOUT ANY WARRANTY; without even the implied warranty of51 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the52 * GNU General Public License for more details.53 *54 * You should have received a copy of the GNU General Public License55 * along with this program; if not, write to the Free Software56 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.57 *58 * M. Welsh, 6 July 199659 *60 *61 */62